油气聚集形成异常高压机理初探

Preliminary Study on the Mechanism of Abnormal High Pressure Formed by Oil and Gas Accumulation

胡黎明

HU Liming

克拉玛依职业技术学院石油工程系, 新疆 克拉玛依 834000

Department of Petroleum Engineering, Karamay Vocational & Technical College, Karamay, Xinjiang 834000, China

异常高压的形成机理十分复杂，是一个未完全解决的学术难题，有待进一步深入研究。通过分析油气运移、聚集成藏与储集层排水特点，从油气"充注"动力、异常高压的定量计算、异常高压的保存与释放等方面，对油气聚集形成异常高压的机理进行了初步探索。结果表明，在生储交界处，油气运移进入储集层的主要动力为毛管压力，生油层孔隙毛管半径越小，油气从生油层向储集层"充注"的动力也越大，生油层孔隙毛管半径是影响储集层中地层压力系数最大值的重要因素之一；在一定地质历史时期，只要运移进入储集层的油气量略大于储集层排出的水量，即可形成较大的异常高压；储集层中的异常高压由盖层通过毛管压力封堵而得以保存；在油气聚集区域之外的储盖交界处不存在毛管压力，储集层可通过盖层向外排水释放压力。油气聚集形成异常高压理论，能够合理解释为什么大多数油气藏的压力高于相同深度的静水液柱压力，地层压力系数略大于1.0，但非常高的异常高压油气藏却很少的客观现实；也能够合理解释较高的异常高压的形成原因。

The formation mechanism of abnormal high pressure is very complex, and it is an unsolved academic problem, which needs to be further studied. By analyzing the characteristics of oil and gas migration, accumulation and reservoir drainage, the mechanism of abnormal high pressure formed by oil and gas accumulation is preliminarily explored from the aspects of "filling" power of oil and gas, quantitative calculation of abnormal high pressure, preservation and release of abnormal high pressure. The results show that the main driving force of oil and gas migration into reservoir is capillary pressure at the junction of reservoir and reservoir. The smaller the radius of pore capillary, the greater the power of oil and gas "filling" from reservoir to reservoir. The radius of pore capillary is one of the important factors affecting the maximum formation pressure coefficient in reservoir. The abnormal high pressure can be formed if the oil and gas volume of reservoir is slightly larger than the water discharged from reservoir; the abnormal high pressure in reservoir can be preserved by capillary pressure plugging; there is no capillary pressure at the reservoir-cap junction outside the oil and gas accumulation area, and the reservoir can release pressure through the drainage of caprock. The theory of abnormal high pressure formed by hydrocarbon accumulation can reasonably explain the fact that the pressure of most reservoirs is higher than that of hydrostatic column at the same depth, and that the formation pressure coefficient is slightly greater than 1.0, but high abnormal high pressure reservoirs is very few; it can also reasonably explain the cause of formation of high abnormal high pressure.

10.11885/j.issn.1674-5086.2019.04.17.01